In typical vehicle engine cooling systems, such as the one shown in FIG. 1, a liquid coolant is circulated through the engine 10 to transport heat away from the engine. For example, relatively low temperature coolant is introduced to channels in the engine. As the coolant circulates through the channels, heat from the engine is transferred to the coolant. The heated coolant then exits the engine, and the relatively hot coolant circulates through a series of passageways internal to a radiator 12 located at the forward end of the vehicle. Airflow through the series of passageways convectively transports heat away, thereby cooling the circulating coolant. The series of passageways is generally provided with fins to improve heat transfer performance. As a result, relatively low temperature coolant exits the radiator and is returned to the engine.
An engine-driven fan 14 is typically provided at the rear side (engine side) of the radiator 52 to enhance the airflow through the radiator 12, significantly increasing the heat transfer from the circulating coolant. The fan 14 is particularly important for maintaining airflow through the radiator when the vehicle is not moving. The fan 14 is oriented to draw air rearwardly through the radiator 12 and past the fan 14 into the engine compartment.
In order to optimize the flow of air drawn through the radiator 12 by the fan 14, a shroud assembly 16 is often provided. As shown in FIG. 1, a known shroud assembly 16 includes a radiator shroud 18 attached the rear side of the radiator 12 to receive air passing through the radiator 12 and to redirect the air toward the fan 14. A ring shroud 20 is attached to the engine 10 and surrounds the fan 14 so that the fan 14 is at least partially disposed within the ring shroud 20, with the tips of the fan blade positioned in close proximity to the ring shroud 20. The ring shroud 20 is secured to the engine 10 with one or more supports 21. The shroud assembly 16 further includes a flexible cylindrical boot 22 secured at one end to the outlet of the radiator shroud 18 and at the other end to the inlet of the ring shroud 20. The boot 22, which may be extruded or rolled from a flat material, is secured to the radiator shroud 18 and the fan ring shroud 20 with band clamps 24.
Presently known shroud assemblies include several inherent disadvantages. First, when the vehicle is assembled, the flexible boot is secured to the ring shroud with a first clamp and held in a compressed state with restraints while the cooling module, i.e., the radiator and radiator shroud are installed. Once the cooling module is installed, the restraints are removed, and the flexible boot expands to seat against the radiator shroud. The boot is then secured to the radiator shroud with a second clamp. This process adds additional time and cost to the assembly process. In addition, the clamps used to secure the boot to the ring shroud and the radiator shroud are prone to failure, which can result in damage to the boot and the fan.
Other presently known shroud assemblies include a shroud ring and boot formed by rolling extruded parts into a ring configuration. In these shroud assemblies, a flexible boot extrusion is threaded into an aluminum ring extrusion, and then the boot extrusion and the ring extrusion are rolled into a ring shape. This process typically results in an undesirable number of distorted or failed parts. In addition, the process adds to the required manufacturing time, thereby further increasing the cost of the parts.